Automobiles are conventionally equipped with a pair of front road wheels that are steered to enable the vehicle to turn left and right as it maneuvers on land. It is also known to provide actuators for steering rear wheels in automobiles. Vehicle steering systems commonly employ a mechanical connection between the driver-operated hand wheel and the front road wheels of an automotive vehicle. As the driver rotates the hand wheel, a mechanical linkage through the vehicle's tie-rods actuate the road wheels sometimes with the assistance of a power assist steering motor or hydraulic piston. The term, “hand wheel” as used herein refers to a driver-operated rotating steering input device, but it need not be round or wheel shaped, though that is the most common configuration.
Recently, steer-by-wire steering systems have been introduced into automotive vehicles to provide road wheel steering function. Included in a typical steer-by-wire steering system is a hand wheel actuator for monitoring the angular position of the steering wheel, and road wheel motor actuators, which are controlled by controllers in response to tracking the sensed angular displacement of the hand wheel from a central or other position. In contrast to prior steering systems, the steer-by-wire steering system does not employ a mechanical linkage between the steering wheel and the individual road wheels. Exemplary of such known steer-by-wire systems is commonly-assigned U.S. Pat. No. 6,176,341, issued Jan. 23, 2001 to Ansari, which is incorporated herein by reference in its entirety.
Along with the advent of steer-by-wire systems, automobile purchasers are always expecting an increased level of driver comfort and convenience. The desirability of placing some instruments, such as environmental and audio system controls on or near the steering wheel has long been recognized. Such controls are currently placed in various locations around the steering wheel, such as along a spoke or integrated in a multi-function stalk switch. As the sophistication of automobile electronics increases, and with the increased popularity of such systems as mobile communications, Global Positioning Satellite (GPS) systems and electronic maps, the locations available to place such controls and displays are not adequate, particularly since any control or display mounted on the hub or spoke of the steering wheel (over the airbag, for example) would turn with the steering wheel and therefore not be useful unless traveling in a relatively straight line.
Accordingly, there is perceived a need for a steering wheel assembly having a stationary hub so that electronic controls and displays are viewable and conveniently provided.